How to wake him up?

In your profile you say that your father is 95 years old and had a stroke. It sounds like he's getting ready to leave this world for the next, so I would just let him sleep. As the body gets ready to transition from this world to the next sleeping a lot is very normal.
If you have access to hospice in Japan, I would certainly bring them on board as they can better answer any questions you may have and they will try their best to keep your father as comfortable as possible.
But in the meantime just let him sleep.

Check with the doctor about this to be sure it isn't being caused by his medication or some other issue. But by the end of her life my mother was probably sleeping 20 hours a day, I like to believe her dream world was a much happier place than her reality.

As a person declines they will sleep more.
As my Husbands dementia progressed he went from sleeping 10 to 12 hours a day to sleeping 22 to 23 hours a day.
The body is working to keep the brain, heart and lungs going and it is conserving energy to sleep.
If everything checks out with his doctor ruling out other reasons this is just part of life and death.

I believe you asked what to do, he doesn't want to eat...

I think you are getting your answers...not the answers you want to hear...

I think you need to get hospice on board..call his doctor..

Let him sleep... keep him comfortable....It's okay..

Are other family members helping you out?

When your dad is awake, is he responsive to you?

please call his doctor and ask for advice. tell doctor that he doesn't want to eat, and wants to sleep more.. If he is not on hospice, he should be at least evaluated for hospice..

when he is sleeping, how is his breathing?

Have him assess through hospice. They will help you with meds, medical care and assistance. My daddy and mama were not ones to stay in bed and when it came to the point when they were not getting out of bed then I called hospice. I got them assess and was given medical supplies and assistance to help them and me.

Thank you....I have to explain about my father a little bit more...He was able to bike until last spring. He still has all his healthy teeth.He got hospitalized last August because he developed acute cholecystitis. He stayed in the hospital for 8 days. These 8days really gave him a huge damage. He developed kidney problem because of the side effect of very strong anti biotic. Also he was constantly on bed during this period. So when he was released from the hospital last August, he could not walk or eat by himself. He started rehabilitation a little by a little and I gave him the best nutritious meal. Slowly he has recovered that now he is able to go to bathroom by himself and had very good appetite until this summer.He is still able to get up from bed by himself and go to bathroom by himself. He is able to change his clothes to pajamas and vise versa. He watches TV. Sometimes he changes channels. Before he got hospitalized, he was reading newspaper everyday, used to go to bank to take care of his finance, used to go for shopping to buy his favorite beer or snacks. He even did laundry and washed dishes. He liked Sudoku and Jigsaw puzzles etc...now he has no interest to almost anything..

Let him sleep

Dont wake him up let him sleep .

I’m going to ask you a question. Is your dad able to sleep well at night?

I ask because my mom had night terrors. She would scream and cry out while she was dreaming. She didn’t sleep well at night, so she caught up on her sleep during the day. She was grateful when I woke her up from a bad dream.

I couldn’t sleep during the day because I had other things to do. I was sleep deprived. I hope you are getting a good night’s rest.